Railroad tanker car manway cover seal

ABSTRACT

A railroad tanker car  10  with a fluid cargo tank  11  and a manway assembly  12  is disclosed. The manway assembly  12  includes a nozzle  17  having a nozzle sealing surface  24  and a cover  18  having a cover sealing surface  33 . An attachment device  19  supplies a closing force to bias the cover  18  toward the nozzle  17 . A fluid seal  51  prevents egress of fluids from and ingress of contaminants into the tank  11 . The seal  51  includes a cover seal member  54 , a nozzle seal member  55 , and an expander  56  that forces the members  54  and  55  against their respective cover and nozzle sealing surfaces. The fluid seal  51  also includes a compression limiting carrier  52  with integral locating tabs  53  that locates the seal  51  and controls the compression of the elastomeric components of the seal  51.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of the filing date of U.S.Provisional Patent Application Ser. No. 61/175,486, filed May 5, 2009,the disclosure of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

This invention relates generally to railroad tanker car manwayassemblies, and more specifically to seals for such assemblies.

BACKGROUND OF THE INVENTION

Railroad tanker cars transport numerous types of fluid cargo. Suchtanker cars may include a tank for carrying the fluid cargo and a manwayassembly for providing access to the interior of the tank for filling orother purposes. Railroad tanker car manway assemblies of this type mayinclude a nozzle located on the top of the tank for providing access tothe tank and a cover for closing the nozzle after filling and duringstorage and transportation of the tanker car.

A seal may be provided between the nozzle and the cover of the manwayassembly to prevent egress of the fluid cargo from the tank and toprevent ingress of dirt and water and other contaminants into the tank.Such seals may be exposed to variations in the chemical composition andphysical properties of various fluid cargos. Such seals may also beexposed to variations in mechanical forces during opening and fillingthrough and closing the manway assembly, variations in ambient weatherconditions of temperature, wind and moisture, and variations in thepressure differential between the inside and the outside of the tank.During such conditions, the integrity of the manway assembly seal shouldbe maintained and the seal should not leak or otherwise fail.

Railroad tanker car manway assembly seals may be replaced on conditiondue to leakage or mechanical damage, or may be replaced at appropriatemaintenance intervals of time and/or number of open and close cycles ofthe manway assembly. Seals that have a longer service life intervalbetween replacements and seals that may be replaced with less time aredesirable.

SUMMARY OF THE INVENTION

This invention provides a railroad tanker car manway assembly and afluid seal for such assembly. The invention further provides a method ofmanufacturing the seal.

The manway assembly includes a nozzle, a cover, and an attachment devicethat secures the cover to the nozzle and applies a closing force to biasthe cover toward the nozzle. The fluid seal is disposed between thenozzle and the cover, and the closing force is applied against oppositesides of the seal by the cover and the nozzle. A compression limitingcarrier of the fluid seal provides a substantially incompressible spacerthat defines a constant and controlled distance between opposing sealingsurfaces of the nozzle and the cover when the attachment device is fullytightened.

The nozzle is a generally round hollow cylinder that is permanentlysecured to the top of the tank of the tanker car. The nozzle providesaccess to the interior of the tank and includes an inner cylindricalsurface, an outer cylindrical surface, and a generally planar annulartop nozzle sealing surface.

The cover is generally flat and round and includes an outwardly facingtop surface and an inwardly facing bottom surface. A generally planarcover sealing surface is disposed on the bottom surface of the cover andis aligned with the nozzle sealing surface.

The fluid seal includes a high compressive strength metallic compressionlimiting carrier. The carrier includes a ring shaped carrier portionhaving a top compression limiting surface that engages the bottomsealing surface of the cover, a bottom compression limiting surface thatengages the top sealing surface of the nozzle, and axially projectingtab portions that cooperatively engage the nozzle to radially locate thering shaped carrier portion relative to the top and bottom sealingsurfaces.

The fluid seal further includes axially spaced apart top and bottomthermoplastic elastomeric seal members. Each seal member includes aconvex seal surface, and the axial distance between the seal surfaces isgreater than the axial distance between the top and bottom compressionlimiting surfaces of the ring shaped carrier. The top convex sealsurface engages and seals against the sealing surface of the cover, andthe bottom convex sealing surface engages and seals against the sealingsurface of the nozzle.

The fluid seal further includes a thermosetting elastomeric expandermember secured to the ring shaped carrier and disposed between the topand bottom seal members. As the attachment device is tightened duringclosing of the cover of the manway assembly, the compression limitingcarrier defines and controls the minimum axial distance between theopposing sealing surfaces of the cover and nozzle and defines themaximum compression of the thermoplastic seal surfaces and of thethermosetting expander. The expander locates and secures the top andbottom seal members relative to the ring shaped carrier portion. Theexpander also provides a controlled axial force against the top andbottom seal members to bias such seal members against their respectivesealing surfaces on the cover and nozzle when the attachment device isfully tightened.

The method of manufacturing the fluid seal includes stamping or cuttingor otherwise forming a carrier portion. The carrier portion is formedwith tab portions as an integral component in which the tab portions areformed in a coplanar alignment relative to the carrier portion. Thecarrier portion is placed in a mold, and a top thermoplastic seal blankand a bottom thermoplastic seal blank and an elastomeric thermosettingexpander blank are preloaded into the mold with an elastomer bondingagent applied between the expander blank and each of the seal blanks.The metallic carrier portion is assembled to the mold, and oneperipheral surface of the metallic carrier portion provides one surfaceof the mold. An elastomer bonding agent is applied between theperipheral surface of the carrier portion and the seals and expander.The mold is closed, with heat applied to vulcanize the elastomericexpander and chemically and mechanically bond the carrier portion andthe top and bottom seals and the expander into a unitary compressionlimiting seal. The tabs are displaced to a substantially perpendicularalignment relative to the carrier portion, either before or during orafter the molding process is completed.

The invention also provides various ones of the additional features andstructures and methods described in the claims set out below, alone andin combination, which claims are incorporated by reference in thissummary of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this invention will now be described in further detailwith reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a railroad tanker car having a manwayassembly according to a preferred embodiment, incorporating certainprinciples of this invention.

FIG. 2 is an enlarged perspective view of the manway assembly, removedfrom the top of the railroad tanker car in FIG. 1.

FIG. 3 is an enlarged perspective view of the fluid seal used in themanway assembly shown in FIG. 2.

FIG. 4 is an enlarged cross sectional view of a portion of the manwayassembly shown in FIG. 2, showing the manway assembly and fluid sealprior to tightening the manway assembly.

FIG. 5 is a view similar to FIG. 4, showing the manway assembly andfluid seal in a fully tightened position.

FIG. 6 is a view similar to FIG. 4, showing another embodiment of thefluid seal according to the present invention.

FIG. 7 is a cross sectional view illustrating the molding step accordingto the method of the present invention, after vulcanization.

DETAILED DESCRIPTION OF THE INVENTION

The principles, embodiments and operation of the present invention areshown in the accompanying drawings and described in detail herein. Thesedrawings and this description are not to be construed as being limitedto the particular illustrative forms of the invention disclosed. It willthus become apparent to those skilled in the art that variousmodifications of the embodiments herein can be made without departingfrom the spirit or scope of the invention.

FIG. 1 illustrates a railroad tanker car 10 having a cargo tank 11, amanway assembly 12, manway access stairs 13, and a manway safety railing14. The cargo tank 11 receives, stores, transports and dispenses avariety of fluids having a wide range of chemical compositions andphysical properties. In the illustrated embodiments of the invention,the cargo tank 11 may be filled with liquid cargo.

Referring to FIG. 2, the manway assembly 12 includes a nozzle 17, acover 18, and an attachment device 19, all of appropriate ferrousmaterial and all disposed and centered along a longitudinal axis 20.FIG. 2 illustrates one of several available designs for the nozzle 17,cover 18 and attachment device 19, and other designs for thesecomponents may alternatively be used without departing from the scope orprinciples of this invention. The materials, design, maintenance,testing and operation of the nozzle 17, cover 18 and attachment device19 may, for example, be according to various options for such componentsset out in the Association of American Railroads (“AAR”) Manual ofStandards and Recommended Practices Specifications for Tank Cars,including appendix D to such Specifications, available at 425 ThirdStreet S.W., Washington, D.C. 20024 (www.aar.orq) the entirety of suchManual being incorporated herein by reference.

The nozzle 17 illustrated in FIG. 2 is a generally round annularcylinder that is welded to the top of the cargo tank 11 in alignmentwith a corresponding access hole (not shown) in the top of the tank 11.The welded joint between the nozzle 17 and the tank 11 provides apermanent and fluid tight connection therebetween. The nozzle 17, asshown in FIGS. 2 and 4, includes a generally cylindrical interiorsurface 22, a generally cylindrical exterior surface 23, and a generallyflat, planar, smooth, annular top sealing surface 24. The nozzle 17provides access to the interior of the cargo tank 11, for filling thetank 11 and other purposes.

As further shown in FIGS. 2 and 4, the cover 18 is generally flat andround and includes a generally flat round top surface 31 and a generallyflat round bottom surface 32. A generally flat, planar, smooth, annularbottom annular sealing surface 33 is machined in the bottom surface 32.The bottom sealing surface 33 and the top sealing surface 24 arelongitudinally aligned (longitudinally opposed), as shown in FIG. 4. Acover handle 34 is secured to the cover 18. The cover 18 may be securedto the nozzle 17 by an appropriate hinge (not shown), so that the cover18 can be rotatably opened and closed relative to the nozzle 17 bylifting on the cover handle 34, to open and close access to the interiorof the cargo tank 11 through the nozzle 17.

Referring to FIG. 2, the attachment device 19 includes a plurality ofbolts 41, only some of which can be seen in FIG. 2. One end of each bolt41 is pivotally secured to stationary lugs 42 located on the exteriorsurface 23 of the nozzle 17 by a suitable pivot pin. The other end ofeach bolt 41 is threaded and receives a suitable nut 43 and washer 44,so that such other end may be secured to lugs 45 located on the cover18. The bolts 41 may be loosened to allow such other end to pivot awayfrom the lugs 45 on the cover 18 to permit opening the cover 17, and thebolts may be tightened when such other end is aligned with the lugs 45to tighten the cover 18 against the nozzle 17.

Referring now to FIGS. 3 and 4 together, a fluid seal 51 includes acompression limiting carrier 52, locating tabs 53 integral with thecarrier 52, a top cover seal member 54, a bottom nozzle seal member 55,and an expander 56. The compression limiting carrier 52 is of a highcompressive strength metallic material. In the preferred embodiment, thecarrier 52 is of United States Society of Automotive Engineers 304stainless steel material. Alternatively, for some applications otherhigh compressive strength materials including high strength plastic andcarbon composites may be used for the carrier 52 and integral tabs 53.The carrier 52 is generally flat, annular and ring shaped, with a topcompression limiting surface 57, a bottom compression limiting surface58, and peripheral surfaces 59 and 60. The surfaces 57 and 58 of thecarrier 52, and the sealing surfaces 33 and 24 of the cover 18 andnozzle 17, respectively, are all centered along the longitudinal axis 20and are all disposed in planes that are generally perpendicular to thelongitudinal axis 20. At least three and preferably four locating tabs53 are provided along and depend from one peripheral surface 60, toalign the fluid seal 51 radially along the axis 20 in alignment with thecover sealing surface 33 and the nozzle sealing surface 24 when thecover 18 is partially or fully opened, and to prevent the fluid seal 51from unintentionally falling into the cargo tank 11 or otherwise movingfrom its position on the nozzle 17.

The top or cover seal member 54 and the bottom or nozzle seal member 55are each of a chemical resistant, thin, low temperature thermoplasticfluoroelastomer material from the polytetrafluoroethylene family ofmaterials. The longitudinal thickness of each seal member 54 and 55 isin the range 0.005 inches to 0.040 inches, to provide adequateresistance to chemical or mechanical degradation while providingadequate flexibility. In the preferred embodiment, this material isavailable commercially under the brand name Dyneon. The surface of theseal member 54 that is arranged to engage and seal against the coversealing surface 33 as shown in FIG. 4, and the surface of the sealmember 55 that is arranged to engage and seal against the nozzle sealingsurface 24 as shown in FIG. 2, each include smooth outwardly convexsurfaces for maximum sealing performance. The longitudinal distance 61between the outwardly convex sealing surfaces of the seal members 54 and55 is greater than the longitudinal thickness 62 of the carrier 52. Thesurfaces of the seal members 54 and 55 that are arranged adjacent theexpander 56 are chemically etched for maximum bonding to the expander56.

The expander 56 is located between the cover seal member 54 and thenozzle seal member 55. The expander 56 substantially entirely fills thevolume defined between the seal members 54 and 55 and the carrierperipheral surface 59, except that a concave void 63 extends around theentire peripheral extent of a radially outwardly facing surface of theexpander 56 to prevent the expander material from being over compressedwhen the attachment device 19 is fully tightened The expander 56 is of alow temperature thermosetting elastomeric polymeric material such asnatural or synthetic rubber and is preferably an elastomeric materialaccording to American Society of Testing Materials D2000. The expander56 includes longitudinally oppositely facing expander surfaces that arebonded to the adjacent surfaces of the seal members 54 and 55. Theradially outwardly facing peripheral surface in which the concave void63 is provided and a radially inwardly facing peripheral surface of theexpander 56 extend longitudinally between the oppositely facing expandersurfaces, with the radially inwardly facing peripheral surface of theexpander 56 being bonded to a peripheral surface, such as surface 59, ofthe carrier 52. In these bonding areas, a heat activated bonding agentsuch as the bonding agent available under the trade name Chemlok isused. The seal members 54 and 55 and the expander 56 together provide anelastomeric seal element 54, 55, 56 for the fluid seal 51.

Referring again to FIG. 4, the seal 51 is illustrated installed inposition between the cover 18 and the nozzle 17, with the cover 18almost fully closed but before any compression of the elastomericelement of the seal 51 has occurred. In this position, the cover sealingsurface 33 and the nozzle sealing surface 24 initially engage thelongitudinally thickest portion of the elastomeric element 54, 55, 56 ofthe fluid seal 51. This longitudinally thickest portion is the locationat which convex seal members 54 and 55 are in an at rest uncompressedstate and are longitudinally spaced apart a maximum distance 61 which,as described above, is greater than the longitudinal thickness 62 of thecompression limiting carrier 52. In this position, the attachment device19 is not yet fully tightened but the nuts 43 and washers 44 of eachbolt 41 may be loosely aligned with the associated cover lugs 45.

When the nuts 43 associated with each of the bolts 41 are fullytightened, the cover 18 and nozzle 19 and fluid seal 51 move to thepositions illustrated in FIG. 5. In this position, the cover 18 andnozzle 17 each tightly engage the top and bottom compression limitingsurfaces 57 and 58, respectively, of the compression limiting carrier52. This position causes the torque required to further tighten the nuts43 to increase significantly, to signal that the nuts are fullytightened and that the compression limiting carrier 52 is tightlycompressed between the cover 18 and the nozzle 17 but is notsubstantially longitudinally deformed by such compression. As thisoccurs, the cover sealing surface 33 moves closer to the nozzle sealingsurface 24, until the minimum distance 62 between these surfaces asdetermined and controlled by the carrier 52 is reached as illustrated inFIG. 5. In this position, the cover seal member 54 is longitudinallycompressed against the surface 33 and the nozzle seal member 55 islongitudinally compressed against the surface 24. The amount of thiscompression is determined by the difference between the distances 61 and62. The sealing force exerted by the seal members 54 and 55 againsttheir respective sealing surfaces 33 and 24 is determined primarily bythe compressive force exerted against these members by the compressionof the expander 56, and is determined to a minor extent by the elasticmemory of the seal members 54 and 55 as they are displaced from their atrest concave positions shown in FIG. 4 to their energized generally flatpositions shown in FIG. 5. The volume of the expander 56 is squeezedlongitudinally and is displaced radially from the position shown in FIG.4 to the position shown in FIG. 5. In this manner, the displacement ofthe cover seal member 54 and of the nozzle seal member 55 are determinedand controlled by the compression limiting carrier 52, and the sealingforce of each of the seal members 54 and 55 is provided by anddetermined by the expander 56 that resists this displacement. Theexpander 56 has a relatively low compression set, so that the seal forceis repeatable time after time to increase the service life of the fluidseal 51. While the seal members 54 and 55 exert a relatively strongsealing force against their respective sealing surfaces 33 and 24, thespecific material used for the seal members 54 and 55 may reduce anytendency of the seal members to stick to such sealing surfaces or anytendency to damage the seal members or the expander even after the cover18 has been closed for a long period of time under adverse ambientweather conditions.

FIG. 6 illustrates an alternative preferred embodiment of thisinvention. In FIG. 6, components that are identical to those shown inFIGS. 1 through 5 are indicated with the same reference numbers as thoseused in FIGS. 1 through 5 while components that are functionally similarbut not structurally identical are indicated by the reference numberused in FIGS. 1 through 5 with a “1” prefix. As shown in FIG. 6, thecover seal member 154 and the nozzle seal member 155 each include twoconcentric outwardly convex sealing ridges instead of the single convexridge configuration for the seal members 54 and 55 shown in FIGS. 1through 5. Other alternative embodiments of the invention are alsocontemplated. For example, the integral tabs 53 may be disposed on theouter periphery of the carrier 52 to cooperate with the exteriorcylindrical surface 23 of the nozzle 17 to locate the fluid seal whilethe elastomeric element 54, 55, 56 may be located on the inner peripheryof the carrier 52. Additionally, one or both peripheral edge surfaces ofthe expander 56, one of which is uncovered in the embodiments describedabove and the other of which is bonded to the surface 59 of the carrier52, may be partially of fully covered by a flexible film of the same orsimilar material as that used for the seal members 54 and 55, butpreferably of a thinner cross section. Still further, the fluid seal 51may be used in different joint configurations and applications, andvariations in size and proportion for the various components of thefluid seal may be incorporated to accommodate the specific joint inwhich the fluid seal is used.

The structure of the fluid seal 51 and its various embodiments shown inthe drawings and described above may minimize or reduce chemical andphysical damage to the components of the fluid seal 51 during openingand filling through and closing the components in which the fluid seal51 is used. Additionally, over compression or under compression of theseal members 54 and 55 and expander 56 may be minimized or reduced oreliminated. This may increase the length of service of the fluid seal 51between required replacements. Additionally, time and complexity of suchreplacement may be minimized.

The method of manufacturing the fluid seal 51 includes stamping orcutting or casting or otherwise forming at least one generally roundcarrier portion. The carrier portion may extend for a full 360 degreecircumference, or it may be formed in partial segments that extend forless than 360 degrees and that are later secured together. The carrierportion is formed with one or more locating tab portions as an integralmember, with the tab portions formed in a coplanar alignment relative tothe carrier portion. As shown in FIG. 7, the formed carrier portion 52with the integral locating tabs 53 is placed in a mold apparatus thatmay include a mold cavity 71 defined by a top mold segment 72, a bottommold segment 73, a side mold segment 74, and the peripheral surface 59of the carrier 52. FIG. 7 illustrates the mold cavity 71 in its closedposition, but the carrier portion 52 is placed in the mold cavity 71when the mold cavity 71 is opened such as by displacing the top moldsegment 72 away from the mold segments 73 and 74. A nozzle seal memberblank in the form of a generally flat annulus or in the form of aslightly concave annulus is placed on the mold segment 73, a circularrope segment like expander blank is placed on the nozzle seal memberblank, and a cover seal member blank in the form of a generally flatannulus or in the form of a slightly concave annulus is placed on theexpander blank. The bonding agent is also applied between each of theseal members and the expander, and also between the carrier peripheralsurface 59 and the expander and seal members. The mold cavity 71 is thenclosed to the position shown in FIG. 7 and heated, to shape andvulcanize the expander 56 and to shape the seal members 54 and 55. Theintegral tabs 53 may be displaced from their original formed positiongenerally coplanar with the carrier 52 before the molding step or duringthe molding step when the mold shown in FIG. 7 is used, or they may beso displaced after the molding step, to complete the manufacture of thefluid seal 51.

Presently preferred embodiments of the invention are shown in thedrawings and described in detail above. The invention is not, however,limited to these specific embodiments. Various changes and modificationscan be made to this invention without departing from its teachings, andthe scope of this invention is defined by the claims set out below.

1. A seal for sealing an opening of a railroad tanker car manwayassembly, the opening being surrounded by a generally annular firstsealing surface and a longitudinally opposed and spaced apart generallyannular second sealing surface, and said seal being interposed betweenthe first and second sealing surfaces, said seal comprising: a generallyannular carrier; a generally annular seal element attached to an outerperipheral surface of the carrier, the seal element being compressiblebetween the first and the second sealing surfaces to provide a fluidtight seal therebetween, and the carrier being substantiallyincompressible relative to the seal element; and and a plurality oflocating tabs depending from an inner or outer periphery of the seal,said tabs being registerable with a corresponding inner or outerperipheral surface of the opening to align the seal coaxially therewith.2. The seal of claim 1 wherein the seal element is formed at least inpart of an elastomeric polymeric material such as a natural or syntheticrubber.
 3. The seal of claim 1 wherein the carrier is formed of a rigidmaterial such as a metal or plastic.
 4. The seal of claim 1 wherein: thecarrier further has opposing first and second compression limitingsurfaces each extending in a generally radial direction; and the sealelement extending circumferentially about said outer peripheral surfaceof the carrier, the seal element further extending axially beyond thefirst and the second compression limiting surfaces.
 5. The seal of anyone of claim 1 or 4, wherein: the seal element includes a first sealmember extending axially beyond said first compression limiting surface,a second seal member extending axially beyond said second compressionlimiting surface, and a circumferential expander extending along andsecured to the outer peripheral surface of the carrier, the carrierbeing disposed intermediate the first and second seal members, the firstand second seal members being secured to the expander, the expanderbeing of elastomeric polymeric material such as a natural or syntheticrubber, and the first and second seal members each being of anelastomeric thermoplastic material.
 6. The seal of claim 5, wherein thefirst sealing surface is disposed on a cover of a tanker manwayassembly, and the second sealing surface is disposed on a nozzle of atanker manway assembly.
 7. The seal of claim 1 wherein the plurality oflocating tabs depend from the outer periphery.
 8. An assemblycomprising: a railroad tanker car manway nozzle having an opening, theopening being surrounded by a first generally annular sealing surfaceand having longitudinally extending inner and outer peripheral surfaces;a cover having a second generally annular sealing surface longitudinallyaligned with said nozzle sealing surface; a generally annular andincompressible carrier; a generally annular seal element attached to anouter peripheral surface of the carrier, the seal element beingcompressed between the first and the second sealing surfaces providing afluid tight seal therebetween; and a plurality of locating tabsdepending longitudinally from an inner or outer periphery of the seal,the tabs being radially aligned with a corresponding inner or outerperipheral surface of the opening and aligning the seal coaxiallytherewith.
 9. The assembly of claim 8 wherein the seal member includes afirst elastomeric seal member and a second elastomeric seal member andan elastomeric expander, said seal members each being of a thermoplasticmaterial, said expander being of a thermosetting material, said sealmembers each being bonded to said expander on longitudinally oppositesides of the expander, and the expander being bonded to the outerperipheral surface of the carrier.
 10. The assembly of claim 9 whereinthe carrier is of a rigid material such as metal or plastic, and saidtabs are integral with said carrier.
 11. The assembly of claim 10wherein: the carrier further has opposing first and second compressionlimiting surfaces each extending in a generally radial direction betweenthe inner and outer peripheral surfaces; and the seal element extendingcircumferentially about said outer peripheral surface of the carrier,the seal element further extending axially beyond the first and thesecond compression limiting surfaces.
 12. A seal for sealing an openingof a railroad tanker car manway assembly, the opening being surroundedby a generally annular first sealing surface and a longitudinallyopposed and spaced apart generally annular second sealing surface, andsaid seal being interposed between the first and second sealingsurfaces, said seal comprising: a generally annular carrier having aninner peripheral surface and an outer peripheral surface and a pluralityof locating tabs depending from one of the inner or outer peripheralsurfaces, said tabs being registerable with a corresponding inner orouter peripheral surface of the opening to align the seal coaxiallytherewith; and a generally annular seal member attached to the other oneof the inner or outer peripheral surfaces of the carrier, the sealmember being compressible between the first and the second sealingsurfaces to provide a fluid tight seal therebetween, wherein the sealmember includes a first elastomeric seal member and a second elastomericseal member and an elastomeric expander, said seal members each being ofa thermoplastic material, said expander being of a thermosettingmaterial, said seal members each being bonded to said expander onlongitudinally opposite sides of the expander, and the expander beingbonded to the other one of the inner or outer peripheral surfaces of thecarrier.
 13. The seal of claim 12 wherein the seal element is formed atleast in part of an elastomeric polymeric material such as a natural orsynthetic rubber.
 14. The seal of claim 12 wherein the carrier is formedof a rigid material such as a metal or plastic.
 15. The seal of claim 12wherein: the carrier further has opposing first and second compressionlimiting surfaces each extending in a generally radial direction; andthe seal element extending circumferentially about said one of the inneror outer peripheral surfaces of the carrier, the seal element furtherextending axially beyond the first and the second compression limitingsurfaces.
 16. The seal of any one of claim 12 or 15, wherein: the sealelement includes a first seal member extending axially beyond said firstcompression limiting surface, a second seal member extending axiallybeyond said second compression limiting surface, and a circumferentialexpander extending along and secured to the other one of the inner andouter peripheral surfaces of the carrier, the carrier being disposedintermediate the first and second seal members, the first and secondseal members being secured to the expander, the expander being ofelastomeric polymeric material such as a natural or synthetic rubber,and the first and second seal members each being of an elastomericthermoplastic material.
 17. The seal of claim 16, wherein the firstsealing surface is disposed on a cover of a tanker manway assembly, andthe second sealing surface is disposed on a nozzle of a tanker manwayassembly.
 18. An assembly comprising: a railroad tanker car manwaynozzle having an opening, the opening being surrounded by a firstgenerally annular sealing surface and having longitudinally extendinginner and outer peripheral surfaces; a cover having a second generallyannular sealing surface longitudinally aligned with said nozzle sealingsurface; a generally annular carrier having an inner peripheral surfaceand an outer peripheral surface and a plurality of locating tabs eachdepending longitudinally from one of the inner or outer peripheralsurfaces, the tabs being radially aligned with a corresponding inner orouter peripheral surface of the opening and aligning the seal coaxiallytherewith; and a generally annular seal element attached to the otherone of the inner or outer peripheral surfaces of the carrier, the sealelement being compressed between the first and the second sealingsurfaces providing a fluid tight seal therebetween, wherein the sealmember includes a first elastomeric seal member and a second elastomericseal member and an elastomeric expander, said seal members each being ofa thermoplastic material, said expander being of a thermosettingmaterial, said seal members each being bonded to said expander onlongitudinally opposite sides of the expander, and the expander beingbonded to the other one of the inner or outer peripheral surfaces of thecarrier.
 19. The assembly of claim 18 wherein the carrier is of a rigidmaterial such as metal or plastic, and said tabs are integral with saidcarrier.
 20. The assembly of claim 19 wherein: the carrier further hasopposing first and second compression limiting surfaces each extendingin a generally radial direction between the inner and outer peripheralsurfaces; and the seal element extending circumferentially about saidone of the inner or outer peripheral surfaces of the carrier, the sealelement further extending axially beyond the first and the secondcompression limiting surfaces.